How long do corticosteroids elevate White Blood Cell (WBC) count?

From the Guidelines

Corticosteroids typically elevate White Blood Cell (WBC) counts for as long as they are being taken, with the effect usually lasting 1-2 days after discontinuation of the medication. The effect of corticosteroids on WBC count is well-documented, with studies showing that steroids like prednisone can cause leukocytosis (elevated WBC count) within hours of administration, with peak effects occurring around 4-8 hours after dosing 1. Some key points to consider when evaluating the impact of corticosteroids on WBC count include:

• The elevation primarily affects neutrophils, while causing a decrease in lymphocytes, eosinophils, and monocytes
• The magnitude of WBC elevation depends on the specific steroid, dosage, and individual patient factors, with higher doses typically causing more significant increases
• This steroid-induced leukocytosis is a normal physiological response and should not be confused with infection
• Healthcare providers should be aware of this effect when interpreting blood tests for patients on steroid therapy, as WBC counts typically return to baseline within 1-2 days after steroid discontinuation It's also important to note that while the study by 1 discusses the risk of hepatitis B reactivation associated with immune suppressive and biological modifier therapies, including low-dose corticosteroid therapies, the key takeaway for WBC count elevation is that the effect is generally short-lived and resolves after discontinuation of the medication. In clinical practice, this means that healthcare providers should consider the potential for elevated WBC counts in patients taking corticosteroids, and interpret blood test results accordingly, taking into account the timing and dosage of steroid administration.

From the Research

Corticosteroid-Induced Leukocytosis

• Corticosteroids are known to cause an increase in white blood cell (WBC) count, a phenomenon referred to as leukocytosis 2, 3, 4, 5.
• The degree of leukocytosis is related to the dosage of corticosteroids administered, with higher doses resulting in greater increases in WBC count 2, 3.
• The timing of leukocytosis also varies, with some studies showing that WBC count peaks at 48 hours after steroid administration 2, while others report that leukocytosis can persist for the duration of therapy 3.

Duration of Leukocytosis

• The duration of corticosteroid-induced leukocytosis is not well-defined, but studies suggest that it can last for several days to weeks 3, 4.
• One study found that leukocytosis reached maximal values within two weeks in most cases, after which the WBC count decreased, but not to pretreatment levels 3.
• Another study reported that the mean WBC count decreased during hospitalization in patients not on steroids, suggesting that leukocytosis may be a transient effect 2.

Factors Influencing Leukocytosis

• The type and dose of corticosteroid, as well as the method and duration of administration, can influence the degree of leukocytosis 3, 5.
• Other factors, such as the presence of infection or immune dysfunction, can also impact the WBC count and may need to be considered when interpreting leukocytosis 4, 6.
• The expression of neutrophil adhesion molecules, such as Mac-1 and L-selectin, may also play a role in corticosteroid-induced leukocytosis, with decreased expression leading to increased WBC count 5.